The present invention relates to power transmission systems and in particular to a multi-range forward/reverse manual drive transmission for use with shaft or chain driven vehicles, such as employed in all-terrain vehicles or similar lightweight vehicles.
With the advent of the snowmobile, outdoor recreation vehicles for off-road use have become increasingly popular. One type of such vehicles are popularly referred to as all-terrain vehicles (ATV'S) and are comprised of a lightweight chassis and molded plastic body, both of which are supported by three or four studded, balloon-like tires. Such ATV'S are extremely mobile and suitably adapted for traveling over various types of ground conditions.
Most typically such vehicles are configured in three or four-wheel designs that employ clutch driven, chain drive power trains (although shaft driven power trains are becoming more prevalent), whereby power is transferred from the engine and clutch transmission to the chain and sprocket associated with the rear axle. Typically, such vehicles provide for four or five speeds forward (with no reverse) and which is sufficient to permit the operator to select the proper speed and gear range for the particular ground conditions.
While such vehicles are generally able to surmount most encountered obstacles, occasionally they bog down or become stuck so as to require the operator to dismount and push or lift the chassis so as to un-stick the vehicle. Alternatively, the operator may establish a rocking motion by intermittently applying power in one or more of the various forward gears until the vehicle frees itself. Such action, however, is somewhat tedious, frustrating and wearing on the clutch so that it is desirable to incorporate a reverse gear feature into the ATV.
While reverse gear features are often encountered in riding lawn mowers or the like, most typically the related power trains are belt driven and, therefore, easily reversed by properly manipulating the V-belts and pulleys. The chain-drive mechanism of the typical ATV does not, however, easily accommodate the reverse gear feature in a ruggedized, yet economical, fashion. A reverse feature has previously been employed in the Suzuki LT125. The reverse drive employed there, however, appears to provide for only one drive range in reverse and requires the operator to first disengage the drive train so as to place it in a neutral range, before separately engaging a second mechanism, whereby the reverse drive is achieved. It should be obvious, however, that such a reverse drive is not advantageous to the typical operator, in that such a multi-step engagement mechanism is rather cumbersome and not conducive to establishing a rocking motion, should it become necessary when unsticking an ATV.
The present invention, however, employs a planetary differential gear assembly mountable to the rear axle and having a plurality of partially meshed primary and secondary, straight-cut planetary gears which may be brought to properly engage associated and centrally displaced input and output gears. The differential housing is selectively and slidably actuable via a lever and associated caliper and counteracting spring and stop for restraining the differential housing and permitting the engagement of the gears in either the forward or the reverse drive direction for each of the various drive ranges of the clutch transmission. Thus, complimentary forward and reverse drives are achievable for each of the speed ranges.
Various reversing transmissions have also been noted in U.S. Pat. Nos. 712,893; 2,131,677; 3,109,326; 759,875; 3,685,371; and 3,908,483. While various of these transmissions employ slidably interacting gear assemblies in conjunction with input and output shafts, none employs or suggests the present inter-meshed, slidable planetary gear system.
The above objects, advantages and distinctions of the present invention as well as various others will, however, become more apparent upon a reading of the following description with respect to the following drawings. It is to be recognized though that the following description is made with respect only to various presently preferred embodiments and considered modifications, although numerous others might be suggest to those of skill in the art. Therefore, the present invention is not to be considered narrowly, but rather broadly, and to include all such equivalent structures as may be made without departing from the spirit and scope of the present invention.